So I just bought my wife a 2020 GMC Sierra 1500 elevation with the 5.3 engine and 10 spd transmission. It is already lifted with a 8” readylift and has 20x12 wheels with 37” tires. Problem I am having is the speedometer is very erratic on speed accuracy. At low speeds it is a few mph off but at highway speeds it is off as much as 35 mph. When it hits 74 mph I get a warning saying I have exceeded the 112 mph limit and it slows down. Also the cruise control will say it’s on but will not set. The dealer installed a hypertech in line speed calibrator and the speed reading is closer but still hits the 112 limit on the highway. And now the check engine light is on. Anyone else experience this? Fixes? Suggestions?
So I just bought my wife a 2020 GMC Sierra 1500 elevation with the 5.3 engine and 10 spd transmission. It is already lifted with a 8” readylift and has 20x12 wheels with 37” tires. Problem I am having is the speedometer is very erratic on speed accuracy. At low speeds it is a few mph off but at highway speeds it is off as much as 35 mph. When it hits 74 mph I get a warning saying I have exceeded the 112 mph limit and it slows down. Also the cruise control will say it’s on but will not set. The dealer installed a hypertech in line speed calibrator and the speed reading is closer but still hits the 112 limit on the highway. And now the check engine light is on. Anyone else experience this? Fixes? Suggestions?
